The Water Cycle

• New lesson editor
• Science
• Primary Education
• Age 9,10

The Water Cycle

Open with the idea that the same water on Earth keeps moving and changing state rather than disappearing.

Learning goal

I can explain how water moves through the water cycle.

What words come to mind when you hear water cycle?

Use this to surface prior knowledge such as rain, clouds, Sun, rivers, evaporation, or sea. Invite students to notice which ideas appear most often.

What is the water cycle?

• The water cycle is the continuous movement of water on Earth

• Water moves between the sea, land and air

• It changes state as it moves

• This cycle is driven by the Sun and gravity

Stress that water is recycled. Students often think new water is made during the cycle.

Why the cycle matters

• It supplies fresh water for plants, animals and people

• It helps control weather and climate

• It moves water through rivers, lakes and groundwater

• Life on Earth depends on it

Evaporation

• Heat from the Sun warms water

• Liquid water changes into water vapour

• This happens a lot in oceans, lakes and rivers

Use the exact term water vapour. Remind students that evaporation happens at the surface of water.

Transpiration

• Plants also add water to the air

• Water leaves leaves through tiny openings

• This process is called transpiration

Keep this distinct from evaporation: transpiration is water released by plants.

Water enters the air

Evaporation + transpiration → water vapour in the atmosphere

This slide summarises the first stage as a simple causal chain.

What makes water change into water vapour?

A

Sun's heat

B

Cold air

C

Gravity

D

Clouds

Checks the first stage of the cycle. Cold air links to condensation, and gravity links to precipitation and run-off.

Complete the first stage of the cycle.

The Sun heats water in oceans, lakes and rivers. This causes and liquid water changes into . Plants also add water to the air by . Together, these processes move water into the atmosphere.

The Sun heats water in oceans, lakes and rivers. This causes

and liquid water changes into

. Plants also add water to the air by

condensation

rain

run-off

groundwater

Correct answers are evaporation, water vapour, transpiration.

Condensation

• Higher in the sky, the air is cooler

• Water vapour loses heat

• It changes back into tiny drops of liquid water

Link this to the common example of water drops forming on a cold window or bottle.

How clouds form

• Tiny water drops gather in the air

• These drops form clouds

• Clouds can be made of water drops and ice crystals

Students may think clouds are made of gas. Clarify that visible clouds are tiny liquid drops or ice crystals.

From vapour to cloud

Cooling air → condensation → cloud droplets

What are clouds mostly made of?

A

Warm steam

B

Tiny water drops

C

Dry air

D

Only smoke

Targets the common misconception named in the content notes: clouds are visible droplets or ice crystals, not gas.

Complete how clouds form.

Higher in the sky, the air is . Water vapour loses heat and happens. The vapour changes into tiny drops of water, and these drops form clouds.

Higher in the sky, the air is

. Water vapour loses heat and

happens. The vapour changes into tiny drops of

warmer

evaporation

gas

soil

Correct answers are cooler, condensation, liquid.

Precipitation

• Cloud droplets join together and grow

• When they become too heavy, they fall

• This falling water is called precipitation

Explain that precipitation is the general name for water falling from clouds.

Types of precipitation

• Rain

• Snow

• Sleet

• Hail

You can briefly note that temperature affects which type forms.

Why water falls

Small droplets join → larger droplets form → gravity pulls them down

Why does precipitation fall from clouds?

A

The Sun lifts it

B

The wind stops

C

Gravity pulls it

D

Plants release it

Checks the causal chain from droplets joining together to gravity pulling them down.

Which is a type of precipitation?

1

Rain

2

Cloud

3

Fog

4

Steam

Collection

• Water collects in rivers, lakes and oceans

• Some water soaks into the ground

• Some water flows over the land as run-off

Use the term run-off for water moving across the ground after rain.

Water underground

• Some water sinks into soil and rock

• This water is called groundwater

• Groundwater can move slowly and feed rivers

Students may not realise that water also travels below the surface, not only in rivers and clouds.

The cycle continues

Collection → evaporation → condensation → precipitation → collection

This is the full cycle summary. Revisit the central idea that water keeps moving and changing state.

Complete what happens after rain.

After precipitation, water can in rivers, lakes and oceans. Some water becomes when it sinks into soil and rock. Some also flows over the land as .

After precipitation, water can

in rivers, lakes and oceans. Some water becomes

when it sinks into soil and rock. Some also flows over the land as

evaporate

condensation

clouds

hail

Correct answers are collect, groundwater, run-off.

Which order shows the water cycle?

A

Condensation, run-off, evaporation, collection

B

Collection, precipitation, evaporation, transpiration

C

Collection, evaporation, condensation, precipitation

D

Precipitation, condensation, collection, freezing

Uses the summary sequence taught on slide 15.

Water changes state

• Liquid water becomes gas during evaporation

• Gas becomes liquid during condensation

• Water can also freeze into solid ice

Make the link to the three states of matter if students have met them before.

Key ideas to remember

• The Sun provides energy for evaporation

• Cooling causes condensation

• Gravity helps precipitation and run-off

• Water is reused again and again

Which change of state happens during condensation?

A

Solid to gas

B

Gas to liquid

C

Liquid to gas

D

Solid to liquid

Connects the water cycle to states of matter on slide 16.

What is one thing you learned about the water cycle?

Which part of this lesson was hardest to understand?

One word you will remember from this lesson

Good answers may include evaporation, clouds, precipitation, gravity, groundwater, or cycle. Use the results to recap the strongest takeaways.

Glossary

water cycle - the continuous movement of water on Earth

evaporation - the change from liquid water to water vapour

transpiration - the release of water vapour from plants

condensation - the change from water vapour to liquid water

precipitation - water that falls from clouds

run-off - water that flows over the land

groundwater - water stored underground